Method for the production of polyetherols

ABSTRACT

The present invention relates to a process for preparing a polyetherol which comprises reacting at least one alkylene oxide with at least one starter compound in the presence of a catalyst of the formula I:
 
M 1   p [M 2   q O n (OH) 2(3−n) ] x   (I),
and to the polyetherols prepared by such a process and to their use for the synthesis of polyurethanes, as fuel additive or as surfactant.

The present invention relates to a process for preparing a polyetherolwhich comprises reacting at least one alkylene oxide with at least onestarter compound in the presence of a multimetal oxide catalyst, andalso to the polyetherols prepared by such a process, in particularpolypropylene glycol or polyethylene glycol, and to their use for thesynthesis of polyurethanes, as fuel additive or as surfactant.

Depending on the starter compounds and alkylene oxides used,polyetherols can be used for a variety of applications. In the synthesisof polyurethanes, in particular, bifunctional or polyfunctionalpolyetherols play an important role as starting materials.

Methods of synthesizing polyetherols using various catalysts are knownin principle from the prior art. Thus, for example, WO 99/44739describes the use of supported double metal cyanide catalysts for thesynthesis of polyether alcohols from alkylene oxides and suitablestarter compounds.

Use of other catalysts for such processes is also described in the priorart. Thus, for example, EP-A 1 002 821 describes metal antimonates andprocesses for preparing polyether polyols using such catalysts. Thecatalysts disclosed in EP-A 1 002 821 are, in particular, antimonates ofalkaline earth metals, metals of groups IIA, IIIA, VA of the PeriodicTable of the Elements or transition metals of groups IIB, IIIB, VB andVIIIB. Furthermore, the reaction of water or polyfunctional alcoholswith an alkylene oxide in the presence of these antimonates as catalystto form polyether polyols is described.

The metal-antimony oxide hydroxides described there as catalyst have acomparatively high hydroxide content. This can lead to chemicalinstability at elevated temperatures in the polyetherol synthesis.Furthermore, the catalysts described there have a comparatively lowspecific BET surface area, which leads to a reduced catalytic activity.

It is an object of the present invention to provide, starting from theprior art, a further process for preparing polyetherols using catalystswhich are more stable at elevated temperature.

We have found that this object is achieved by a process for preparing apolyetherol which comprises reacting at least one alkylene oxide with atleast one starter compound in the presence of a catalyst, wherein thecatalyst used is a multimetal oxide compound of the formula I:M¹ _(p)[M² _(q)O_(n)(OH)_(2(3−n))]_(x)  (I),where

-   -   M¹ is at least one element of groups IA, IIA, lIIA, IVA, VA, IB,        IIB, IIIB, IVB, VB, VIB, VIIB and/or VIIIB of the Periodic Table        of the Elements,    -   M² is at least one element of groups IVA, VA and/or VIA of the        Periodic Table of the Elements,    -   n is a fraction or integer from 2 to 3, in particular from        greater than 2 to 3,    -   p is 0 or a fraction or integer greater than 0,    -   q is a fraction or integer greater than 0 and    -   x is a fraction or integer from 1 to 20.

According to the present invention, the metal M¹ is at least one elementof one of the groups IA, IIA, IIIA, IVA, VA, IB, IIB, IIIB, IVB, VB,VIB, VIIB and/or VIIIB of the Periodic Table of the Elements. Inparticular, the metal M¹ is selected from the group consisting ofaluminum, tin, magnesium, titanium, zirconium, cadmium, lanthanum andzinc, particularly preferably zinc and aluminum. The metal M² is atleast one element of groups IVA, VA and/or VIA of the Periodic Table ofthe Elements. M² is preferably selected from the group consisting ofarsenic, antimony, bismuth, tin, germanium, selenium and tellurium,particularly preferably arsenic, antimony or arsenic and antimony, inparticular antimony.

The catalysts used according to the present invention thus have an OH/Oratio of from 0 to 1, in particular from 0 to less than 1. As a resultof the comparatively small proportion of OH groups, the multimetal oxidecompounds used as catalyst have an improved thermal stability.

Such multimetal oxide compounds can be prepared inexpensively, forexample from simple starting compounds of the metals M¹ and M², e.g.salts, oxide hydroxides, or oxides of the metals M¹ and M². Inprinciple, it is possible to use all suitable salts known to thoseskilled in the art, in particular water-soluble salts such as chlorides,acetates, nitrates or acetylacetonates. The multimetal oxide compoundsused according to the present invention as catalyst are preferablyprepared from a salt of the metal M¹ and an oxide, oxide hydroxide orhydroxide of the metal M².

These simple starting compounds of the metals M¹ and M² can, inparticular, be reacted either in a solid-state reaction, for example bymeans of calcination, or in solution or in suspension in a solvent, inparticular in water. It can also be advantageous to use the metal M²initially in a lower oxidation state and to oxidize this to the desiredoxidation state before or during the reaction with the salt of the metalM¹.

The reaction of the starting compounds in the preparation of thecatalyst in the presence of a solvent is preferably carried out atelevated temperatures, in general above 40° C., for example at least 60°C., preferably at least 70° C., in particular at least 80° C. or atleast 90° C. The suspension obtained in this case can be freed of thesolvent. Drying can be carried out, for example, by means of spraydrying. However, it is likewise possible to dry the catalyst by means offreeze drying or conventional drying, i.e., for example, by filtrationor centrifugation, washing and subsequent drying, for example atelevated temperature. The product obtained is then preferably calcined.The calcination step is preferably carried out at from 100° C. to 700°C., for example from 200° C. to 650° C., preferably from 200 to ≦200°C., particularly preferably from 250 to ≦580° C., frequently ≦550° C. Ingeneral, calcination is carried out for a period of from 10 minutes to anumber of hours. The calcination can generally be carried out inert gasor under a mixture of inert gas and oxygen, e.g. air, or else under pureoxygen. Calcination under a reducing atmosphere is also possible. Ingeneral, the calcination time required decreases with increasingcalcination temperature.

Multimetal oxide compounds having M²=antimony which are suitable ascatalyst in the process of the present invention are described, forexample, in WO 99/51341 and DE-A 24 07 677, whose relevant contents arefully incorporated by reference.

Antimonates of the formula I in which M² is antimony have been found tobe particularly useful in the process of the present invention.

The multimetal oxide compounds are obtainable, for example, by themethods described in detail in DE-A 24 076 77.

If M² in the formula I is antimony, preference is given to a procedurein which antimony trioxide and/or Sb₂O₄ is oxidized in an aqueous mediumby means of hydrogen peroxide in an amount which is equal to or abovethe stoichiometric amount at from 40 to 100° C. to form antimony(V)oxide hydroxide hydrate, aqueous solutions and/or suspensions ofsuitable starting compounds of the remaining elemental constituents ofthe multimetal oxide compounds are added before this oxidation, duringthis oxidation and/or after this oxidation, NH₃ is added if appropriate,the mixture is subsequently stirred for a definite time at from 40 to100° C. if appropriate, the resulting aqueous mixture is then dried,preferably spray dried at an inlet temperature of from 200 to 600° C.and an outlet temperature of from 80 to 150° C., and the intimate drymixture is then calcined as described. Addition of NH₃ enables the pH ofthe reaction mixture to be altered. In many cases, it can beadvantageous to add a stoichiometric amount of NH₃ based on the amountof the metal salt, but this is not absolutely necessary.

In the above-described process, it is possible to use, for example,aqueous hydrogen peroxide solutions having an H₂O₂ content of from 5 to33 or more % by weight. A subsequent addition of suitable startingcompounds of the remaining elemental constituents of the multimetaloxide compounds is advisable particularly when these can result incatalytic decomposition of the hydrogen peroxide. Of course, it wouldalso be possible to isolate the resulting antimony(V) oxide hydroxidehydrate from the aqueous medium and, for example, intimately mix it drywith suitable finely divided starting compounds of the remainingelemental constituents of the multimetal oxide compounds andsubsequently calcine this intimate mixture as described.

After calcination is complete, the multimetal oxide compounds can becomminuted once again, for example by wet or dry milling, e.g. in a ballmill or by means of jet milling.

A preferred method of preparing the multimetal oxide compounds isfirstly to convert antimony trioxide and/or Sb₂O₄ in an aqueous mediuminto a, preferably finely divided, Sb(V) compound, e.g. Sb(V) oxidehydroxide hydrate, by means of hydrogen peroxide, admix the resultingaqueous mixture with an ammoniacal aqueous solution of a water-solublesalt, for example an acetate, of the metal M¹, stir the resultingaqueous mixture for a further period and dry it, e.g. by spray drying asdescribed, and calcine the resulting powder as described, if desiredafter subsequent compounding with water and then extrusion and drying.

In a preferred embodiment, the present invention therefore provides aprocess for preparing a polyetherol in which Sb₂O₃ or Sb₂O₄ is used forpreparing the respective multimetal oxide compound.

The multimetal oxide compounds of the formula I have particularlyadvantageous catalytic properties in the preparation of polyetherols.

According to the present invention, the catalyst used in the process forpreparing a polyetherol is preferably a multimetal oxide compound of theformula I which has at least one of the following properties:

-   -   (1) p is an integer or fraction from 0 to 3, preferably from 0.5        to 2, in particular from 0.9 to 1.1, for example 1;    -   (2) q is an integer or fraction from greater than 0.5 to 3,        preferably from 0.7 to 2, in particular from 0.9 to 1.1, for        example 1;    -   (3) x is an integer or fraction from 1.2 to 14, preferably from        1.4 to 7, in particular from 1.6 to 5, for example from 1.8 to        3.2;    -   (4) the metal M² is antimony and/or arsenic;    -   (5) the metal M¹ is selected from the group consisting of        aluminum, tin, magnesium, titanium, zirconium, cadmium,        lanthanum and zinc; and    -   (6) n is an integer or fraction from 2 to 3, preferably from        greater than 2 to 3.

In a specific embodiment, the present invention provides a process forpreparing a polyetherol in which the catalyst used is a multimetal oxidecompound of the formula I which has at least one of the followingproperties:

-   -   (1′) p is 1;    -   (2′) q is 1;    -   (3′) x is an integer or fraction from 1.8 to 3.2;    -   (4′) the metal M² is antimony;    -   (5′) the metal M¹ is selected from the group consisting of zinc        and aluminum; and    -   (6′) n is an integer or fraction from greater than 2 to 3.

It is likewise possible in the context of the present invention for themultimetal oxide compound used as catalyst to have two or more of theproperties (1′) to (6′). In particular, a multimetal oxide compound usedas catalyst in the process of the present invention can have all of theproperties (1′) to (6′).

In a particularly preferred embodiment, the present invention provides aprocess in which the catalyst used has the formulaZn[SbO_(n)(OH)_(2(3−n))]₂ or Al[SbO_(n) (OH)_(2(3−n))]₃, where n is aninteger or fraction from 2 to 3, preferably from greater than 2 to 3.

In a preferred embodiment, the present invention provides a process forpreparing a polyetherol in which the metal M¹ is zinc or aluminum.

In general, the multimetal oxide compound used as catalyst in a processof the present invention is present essentially in crystalline form.I.e. the multimetal oxide compound generally consists essentially ofsmall crystallites whose maximum dimension is typically from 0.05 to 100μm. Of course, however, the multimetal oxide compound can also beamorphous and/or crystalline.

Suitable multimetal oxide compounds have, for example, a crystalstructure which is isotypic with the structure of the mineral partzite,i.e. Cu₂Sb₂(O,OH)₇. The present invention therefore also provides aprocess for preparing a polyetherol in which the multimetal oxidecompound of the formula I has a crystal structure which is isotypic withthe structure of the mineral partzite.

The catalytic activity of the multimetal oxide compounds used is also,for example, dependent on the specific BET surface area of thecompounds. The specific BET surface are determined by the method ofBrunauer, Emmett and Teller is influenced, for example, by thecalcination temperature. The multimetal oxide compounds used in theprocess of the present invention have, for example, a specific BETsurface area of from 15 to 500 m²/g, preferably from 20 to 200 m²/g, inparticular from 20 to 150 m²/g, particularly preferably from 40 to 150m²/g.

In a preferred embodiment, the present invention therefore provides aprocess for preparing a polyetherol in which the multimetal oxidecompound of the formula I has a specific BET surface area of from 15 to500 m²/g.

The catalyst concentration used in the process of the present inventionis less than 5.0% by weight based on the product, preferably less than2.0% by weight, in particular less than 1.5% by weight, particularlypreferably less than 1.0% by weight. According to the present invention,the catalyst can, for example, be used as a suspension or as a fixed-bedcatalyst.

As starter compounds in the process of the present invention, it ispossible to use all the suitable compounds containing active hydrogenwhich are known to those skilled in the art. According to the presentinvention, preference is given to using OH-functional starter compounds,for example OH-monofunctional or OH-polyfunctional compounds.

In a further embodiment, the present invention therefore provides aprocess for preparing a polyetherol in which the starter compound is anOH-monofunctional or OH-polyfunctional compound.

Examples of starter compounds which are suitable for the purposes of thepresent invention are the following compounds: water, organicdicarboxylic acids such as succinic acid, adipic acid, phthalic acid andterephthalic acid, aliphatic and aromatic, unsubstituted orN-monoalkyl-, N,N-dialkyl- and N,N′-dialkyl-substituted diamines havingfrom 1 to 4 carbon atoms in the alkyl radical, e.g. unsubstituted,monoalkyl-substituted and dialkyl-substituted ethylenediamine,diethylenetriamine, triethylenetetramine, 1,3-propylenediamine, 1,3- or1,4-butylenediamine, 1,2-, 1,3-, 1,4-, 1,5- and1,6-hexamethylenediamine, phenylenediamines, 2,3-, 2,4- and2,6-toluenediamine and 4,4′-, 2,4′- and 2,2′-diaminodiphenylmethane.Further possible starter molecules are: alkanolamines such asethanolamine, N-methylethanolamine and N-ethylethanolamine,dialkanolamines such as diethanolamine, N-methyldiethanolamine andN-ethyl-diethanolarnine, and trialkanolamines such as triethanolamine,and ammonia and also monohydric or polyhydric alcohols such asmonoethylene glycol, 1,2- and 1,3-propanediol, diethylene glycol,dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerol,trimethylolpropane, pentaerythritol, sorbitol and sucrose. Preferredpolyether alcohols are addition products of ethylene oxide and/orpropylene oxide onto water, monoethylene glycol, diethylene glycol,1,2-propanediol, dipropylene glycol, glycerol, trimethylolpropane,ethylenediamine, triethanolarnine, pentaerythritol, sorbitol and/orsucrose, either individually or as mixtures.

The starter compounds can, according to the present invention, also beused in the form of alkoxylates, in particular those having a molecularweight M_(w) in the range from 62 to 15000 g/mol.

However, macromolecules having functional groups containing activehydrogen atoms, for example hydroxyl groups, are likewise suitable, inparticular those mentioned in WO 01/16209.

Particularly preferred starter compounds are monofunctional orpolyfunctional alcohols having from 1 to 24 carbon atoms, according tothe present invention particularly preferably starter compounds havingfrom 8 to 15 carbon atoms, in particular from 10 to 15 carbon atoms, forexample tridecanol.

Alcohols which are particularly useful for the purposes of the presentinvention are thus, in particular, octanol, nonanol, decanol, undecanol,dodecanol, tridecanol, tetradecanol, pentadecanol, ethylhexanol,propylheptanol, fatty alcohols having from 10 to 18 carbon atoms, oxoalcohols, isooctanol, iso-nonanol, isodecanol, isoundecanol,isododecanol, isotridecanol, isotetradecanol, isopentadecanol,preferably isodecanol, 2-propylheptanol, tridecanol, iso-tridecanol ormixtures of C13 to C15 alcohols.

In a further preferred embodiment, the present invention thereforeprovides a process for preparing a polyetherol in which the startercompound is a monofunctional or polyfunctional alcohol having from 1 to24 carbon atoms.

In the process of the present invention, it is in principle possible touse all suitable epoxides. Suitable epoxides include, for example,C₂-C₂₀-alkylene oxides such as ethylene oxide, propylene oxide,1,2-butylene oxide, 2,3-butylene oxide, isobutylene oxide, penteneoxide, hexene oxide, cyclohexene oxide, styrene oxide, dodecene epoxide,octadecene epoxide and mixtures of these epoxides. Ethylene oxide,propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide and penteneoxide are especially useful, with particular preference being given toethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxideand isobutylene oxide.

In a preferred embodiment, the present invention therefore provides aprocess for preparing a polyetherol in which the alkylene oxide isethylene oxide, propylene oxide or butylene oxide or a mixture of two ormore thereof.

According to the present invention, the alkylene oxide can also be usedin the form of a mixture. A mixture can advantageously be, for example,a raffinate I oxide mixture. For the purposes of the present invention,a raffinate I oxide mixture is a mixture obtained by oxidation of araffinate I stream.

The composition of the raffinate I oxide mixture is dependent on theraffinate stream used for its preparation. The raffinate I mixtureobtained from a steam cracker comprises isobutene, 1-butene and2-butene. This mixture can be oxidized directly to give thecorresponding oxiranes as a raffinate I oxide mixture.

The use of a raffinate I oxide mixture in the process of the presentinvention has the advantage that the alkylene oxide mixture can bereacted essentially without prior purification and separation of theindividual components. This results in a particularly inexpensiveprocess because of the use of cheap starting materials. In a specificembodiment, the present invention therefore provides a process forpreparing a polyetherol in which a raffinate I oxide mixture is reacted.The raffinate I oxide mixture can be used essentially withoutpurification or after prior purification.

According to the present invention, the process for preparing thepolyetherols is carried out at from 100° C. to 180° C., preferably from110° C. to 150° C. The process is preferably carried out at pressures offrom 0 bar to 50 bar.

The present invention likewise provides for the use of a multimetaloxide compound of the formula I as catalyst for preparing a polyetherolfrom at least one alkylene oxide and at least one starter compound:M¹ _(p)[M² _(q)O_(n)(OH)_(2(3−n))]_(x)  (I),where

-   -   M¹ is at least one element of groups IA, IIA, IIIA, IVA, VA, IB,        IIB, IIIB, IVB, VB, VIB, VIIB and/or VIIIB of the Periodic Table        of the Elements,    -   M² is at least one element of groups IVA, VA and/or VIA of the        Periodic Table of the Elements,    -   n is a fraction or integer from 2 to 3, in particular from        greater than 2 to 3,    -   p is 0 or a fraction or integer greater than 0,    -   q is a fraction or integer greater than 0 and    -   x is a fraction or integer from 1 to 20.

Likewise, the present patent application provides polyetherols, inparticular polypropylene glycol or polyethylene glycol, obtainable by aprocess which comprises reacting at least one alkylene oxide with atleast one starter compound in the presence of a catalyst, wherein amultimetal oxide compound of the formula I is used as catalyst:M¹ _(p)[M² _(q)O_(n)(OH)_(2(3−n))]_(x)  (I),where

-   -   M¹ is at least one element of groups IA, IIA, IIIA, IVA, VA, IB,        IIB, IIIB, IVB, VB, VIB, VIIB and/or VIIIB of the Periodic Table        of the Elements,    -   M² is at least one element of groups IVA, VA and/or VIA of the        Periodic Table of the Elements,    -   n is a fraction or integer from 2 to 3, in particular from        greater than 2 to 3,    -   p is 0 or a fraction or integer greater than 0,    -   q is a fraction or integer greater than 0 and    -   x is a fraction or integer from 1 to 20.

The polyetherols obtained according to the present invention have, forexample, a narrow molecular weight distribution and a low content ofhigh molecular weight impurities.

Depending on the type of starter compound used and the alkylene oxide,the polyetherols of the present invention are suitable for variousapplications. Polyetherols obtained by reacting monofunctional startercompounds with one or more alkylene oxides are particularly useful asfuel additives or surfactants. If starter compounds having two or moreactive functional groups are used, the polyetherols obtained areparticularly suitable for use in the synthesis of polyurethanes.

The present invention therefore also provides for the use of apolyetherol obtainable by the process of the present invention or apolyetherol obtainable using a multimetal oxide compound according tothe present invention for the synthesis of polyurethanes, as fueladditive or as surfactant.

In addition, the polyetherols obtained by a process of the presentinvention can also be used in surface coating compositions, as concretefluidizers, as emulsifiers or as dispersants.

The present invention is illustrated by the following examples.

EXAMPLES

1. Method of preparing the catalyst:

583.0 g of Sb₂O₃ (2 mol; from Merck KGaA, Darmstadt) were suspended withstirring in 4 l of water. The suspension obtained was admixed at roomtemperature (25° C.) with 498.6 g of a 30% strength by weight aqueousH₂O₂ solution (4.4 mol of H₂O₂; from Merck KGaA, Darmstadt). Thesuspension was subsequently heated to about 100° C. over a period of 1hour while stirring and was refluxed at this temperature for 5 hours. Asolution of 438.98 g of Zn(CH₃COO)₂·2H₂O (2 mol; from Merck KGaA,Darmstadt) was added over a period of 30 minutes to the suspension whichwas still at 100° C., during which the temperature of the total aqueousmixture dropped to about 65° C. At this temperature, 272.0 g of a 25%strength by weight aqueous ammonia solution (4 mol) were subsequentlyadded. The aqueous suspension was stirred for another 2 hours at 80° C.and subsequently cooled to room temperature (25° C.). The aqueoussuspension was finally spray dried (inlet temperature: 365° C., outlettemperature: 110° C.). This gave a free-flowing spray-dried powder(product A).

Part of the spray-dried powder (product A) was heated to 150° C. at aheating rate of 1°/min in a rotary tube furnace (1 1 capacity) whilepassing 10 standard l/h of air through the furnace and was maintained atthis temperature for 2 hours (product B).

A further part of the spray-dried powder (product A) was heated in ananalogous manner to a calcination temperature of 200° C. and maintainedat this temperature for 2 hours (product C).

Portions of the product C were heated at a heating rate of 3°/min to acalcination temperature of 300° C. (product D), 400° C. (product E),500° C. (product F), 600° C. (product G) and 700° C. (product H) and ineach case maintained at the respective temperature for 2 hours.

The resulting products A to H were characterized by various methods(Table 1). X-ray diffraction studies indicated that all products (A-H)were clearly crystalline. The products A-F obtained at calcinationtemperatures of ≦500° C. displayed the XRD pattern 07-0303 in the JCPDScard index, demonstrating the presence of a crystal structure which isisotypic with the cubic structure of the mineral partzite[partzite=Cu₂Sb₂(O,OH)₇]. The XRD pattern of partzite also displays asequence of reflections analogous to the XRD pattern of cubic Sb₆O₁₃(JCPCS card index no. 33-0111). Measurement of the X-ray reflections forthe products A-F obtained at calcination temperatures of ≦500° C. gavethe following values: Reflection d [Å] I [%] 1 5.87 ± 0.04 20 ± 15 23.07 ± 0.03 30 ± 20 3 2.94 ± 0.03 100 4 2.55 ± 0.03 30 ± 15 5 2.34 ±0.03 7 ± 6 6 1.96 ± 0.03 14 ± 10 7 1.80 ± 0.03 50 ± 20 8 1.72 ± 0.03 15± 13 9 1.55 ± 0.02 14 ± 12 10 1.53 ± 0.02 40 ± 20 11 1.47 ± 0.02 12 ± 10

On the other hand, the calcination products G and H, which were obtainedat temperatures of ≧600° C., displayed the XRD pattern 38-0453 and thushad the tetragonal crystal structure of anhydrous ZnSb₂O₆ (ordonezite).

Furthermore, the specific BET surface area of the calcination productswas determined (in accordance with DIN 66 131 by gas adsorption (N₂)using the method of Brunauer, Emmett and Teller). The products which hadbeen heated at from 150 to 400° C. had the same BET surface area as theuncalcined spray-dried powder (62 m²/g). As the calcination temperatureincreased, the specific BET surface areas decreased (cf. Table 1).

Some of the calcination products were also analyzed to determine theircomposition (Table 1). The measured proportions by weight of Zn, Sb(and, if present, ammonium and acetate) were used to calculate theremaining content of O²⁻ and (OH)⁻ in each of the samples. Thesecompositions are summarized in Table 1 (“Stoichiometry from chemicalanalysis”). The value of n was calculated from the oxide and hydroxidecontents of the zinc antimony oxides (Table 1).

When the calcination products A to H were heated from room temperature(25° C.) to 1000° C. at a heating rate of 5° C./min in air (flow rate:70 cm³ of air/min) in a DTG-TG apparatus (Netzsch STA 429), the weightof the sample decreased as the temperature increased. In Table 1,“weight loss (DTG)” gives the values for the weight loss given by thedifference between the initial weights of the samples in the DTG-TGapparatus and the weights of the samples at 1000° C. in the DTG-TGapparatus.

The calculated proportions of O²⁻ and (OH)⁻ in the products A to Hcalculated from the proportion by weight of Zn, Sb (and, if present,ammonium and acetate), which could be converted directly into an nvalue, agreed well with the weight loss of the samples observed in theDTG-TG.

2. Alkoxylation of diols (DPG) in the presence of a zinc antimonatecatalyst

2.1 Dipropylene glycol+PO (experiment E 243/01)

33.5 g (0.25 mol) of dipropylene glycol were mixed with 1.5 g (1% byweight based on the total batch) of zinc antimony oxide (Example 1,product H, Table 1).

The starter mixture was dewatered at 110° C. under reduced pressure (20-25 mbar) for 1.5 hours. The reaction mixture was then placed in a 300 mlpressure autoclave. After pressure testing and making inert withnitrogen, the reaction mixture was heated to 135° C. and 116 g (2.0 mol)of propylene oxide gas were introduced in portions of 50 ml by means ofan ISCO precision pump. This resulted in an increase in the internalpressure in the reactor to 10-14 bar. The mixture was subsequentlyallowed to react further under these conditions for 10 hours. At the endof the reaction, the mixture was cooled to 50° C. With the offgas valveopen, the mixture was stirred for 3 hours at 50° C., purged 3 times withnitrogen and cooled to room temperature and the mass balance wascalculated from the amount of product obtained. According to the massbalance, a molar conversion of 1:1.01 (starter:PO) was achieved. Theproduct obtained was filtered under pressure through a deep-bed filter.

The product obtained had a polydispersity of D=1.01 (measured by meansof GPC), a molecular weight of M_(w)=151.7 g/mol (measured by means ofGPC), an iodine number of IN(K)<1 g of iodine/100 g and a residual metalcontent of 12 ppm of antimony and 1 ppm of zinc.

Dipropylene glycol+PO (experiment E 247/01)

33.5 g (0.25 mol) of dipropylene glycol were mixed with 1.5 g (1% byweight based on the total batch) of zinc antimony oxide (Example 1,product E, Table 1). The starter mixture was dewatered at 110° C. underreduced pressure (20- 25 mbar) for 1.5 hours. The reaction mixture wasthen placed in a 300 ml pressure autoclave. After pressure testing andmaking inert with nitrogen, the reaction mixture was heated to 135° C.and 116 g (2.0 mol) of propylene oxide gas were introduced in portionsof 50 ml by means of an ISCO precision pump. This resulted in anincrease in the internal pressure in the reactor to 15-16 bar. Themixture was subsequently allowed to react further under these conditionsfor 10 hours. At the end of the reaction, the mixture was cooled to 50°C. With the offgas valve open, the mixture was stirred for 3 hours at50° C., purged 3 times with nitrogen and cooled to room temperature andthe mass balance was calculated from the amount of product obtained.According to the mass balance, a molar conversion of 1:1.1 (starter:PO)was achieved. The product obtained was filtered under pressure through adeep-bed filter.

The product obtained had a polydispersity of D=1.02 (measured by meansof GPC), a molecular weight of M_(w)=156.2 g/mol (measured by means ofGPC), an iodine number of IN(K) of 1 g of iodine/100 g and a residualmetal content of 510 ppm of antimony and <1 ppm of zinc.

2.3 Comparative example: Dipropylene glycol+PO (experiment E 248/01)

33.5 g (0.25 mol) of dipropylene glycol were mixed with 1.5 g (1% byweight based on the total batch) of ZnSb₂O_(0.48)(OH)_(11.04){=Zn[SbO_(0.24)(OH)_(2(3−0.24))]₂}(prepared as described in Example 1 ofEP-A 1 002 821, catalyst A, BET surface area: 11.5 m²/g). The startermixture was dewatered at 110° C. under reduced pressure (20-25 mbar) for1.5 hours. The reaction mixture was then placed in a 300 ml pressureautoclave. After pressure testing and making inert with nitrogen, thereaction mixture was heated to 135° C. and 116 g (2.0 mol) of propyleneoxide gas were introduced in portions of 50 ml by means of an ISCOprecision pump. This resulted in an increase in the internal pressure inthe reactor to 15 bar. The mixture was subsequently allowed to reactfurther under these conditions for 10 hours. At the end of the reaction,the mixture was cooled to 50° C. With the offgas valve open, the mixturewas stirred for 3 hours at 50° C., purged 3 times with nitrogen andcooled to room temperature and the mass balance was calculated from theamount of product obtained. According to the mass balance, a molarconversion of 1:1.8 (starter:PO) was achieved. The product obtained wasfiltered under pressure through a deep-bed filter.

The product obtained had a polydispersity of D=1.075 (components in thehigher molecular weight range, measured by means of GPC), a molecularweight of M_(w)=181.3 g/mol (measured by means of GPC), an iodine numberof IN(K) <1 g of iodine/100 g and a residual metal content of 145 ppm ofantimony and 9 ppm of zinc. TABLE 1 Zinc antimony oxides, prepared fromSb₂O₃ Weight loss Calcination Chem. from specific BET temp. analysis [%by wt.] Stoichiometry from composition Weight loss surface area Product[° C.] Zn Sb NH₄ CH₃COO chemical analysis n [%] (DTG) [%] XRD pattern[m²/g] A none 15.4 56 0.67 1.7 Zn[SbO_(2.52)(OH)_(2(3−2.52))]₂ 2.52 6.46.3 Cu₂Sb₂(O,OH)₇ 62 B 150 15.5 56 0.57 1.4Zn[SbO_(2.50)(OH)_(2(3−2.50))]₂ 2.50 6.2 5.6 Cu₂Sb₂(O,OH)₇ 61 C 200 15.757 0.44 0.79 Zn[SbO_(2.60)(OH)_(2(3−2.60))]₂ 2.60 4.6 4.2 Cu₂Sb₂(O,OH)₇63 D 300 16.0 59 0.20 0.02 Zn[SbO_(2.84)(OH)_(2(3−2.84))]₂ 2.84 1.6 1.7Cu₂Sb₂(O,OH)₇ 63 E 400 Cu₂Sb₂(O,OH)₇ 62 F 500 16.2 60Zn[SbO_(2.98)(OH)_(2(3−2.98))]₂ 2.98 0.13 1.2 Cu₂Sb₂(O,OH)₇ 58 G 600ZnSb₂O₆ 46 H 700 ZnSb₂O₆ 1

1-9. (canceled)
 10. A process for preparing a polyetherol comprisingreacting at least one alkylene oxide with at least one starter compoundin the presence of a catalyst, wherein the catalyst is a multimetaloxide compound of the formula I:M¹ _(p)[M² _(q)O_(n)(OH)_(2(3−n))]_(x)  (I), where M¹ is at least onemetal selected from the group consisting of IA, IIA, IIIA, IVA, VA, IB,IIB, IIIB, IVB, VB, VIB, VIIB and VIIIB of the Periodic Table of theElements, M² is at least one element of groups IVA, VA and/or VIA of thePeriodic Table of the Elements, n is an integer or fraction from greaterthan 2 to 3, p is 1, q is a fraction or integer greater than 0 and x isa fraction or integer from 1 to 20, wherein the multimetal oxidecompound of the formula I has a specific BET surface area of from 15 to500 m²/g.
 11. The process as claimed in claim 10, wherein the catalystis a multimetal oxide compound of the formula I which has at least oneof the following properties: (2′) q is 1; (3′) x is an integer orfraction from 1.8 to 3.2; (4′) the metal M² is antimony; (5′) the metalM¹ is at least one selected from the group consisting of zinc andaluminum.
 12. The process as claimed in claim 10, wherein the metal M¹is zinc or aluminum.
 13. The process as claimed in claim 10, wherein themultimetal oxide compound of the formula I has a crystal structure whichis isotypic with the structure of the mineral partzite.
 14. The processfor preparing a polyetherol as claimed in claim 10, wherein themultimetal oxide compound is prepared using Sb₂O₃ or Sb₂O₄.
 15. Theprocess for preparing a polyetherol as claimed in claim 10, wherein thestarter compound is an OH-monofunctional or OH-polyfunctional compound.16. A polyetherol obtained by a process as claimed in claim 10.